We report on a study of the electronic and magnetic properties of the triangular antiferromagnetic {Cu3} single-molecule magnet, based on spin density functional theory. Our calculations show that the low-energy magnetic properties are correctly described by an effective three-site spin s=1/2 Heisenberg model, with an antiferromagnetic exchange coupling J≈5 meV. The ground state manifold of the model is composed of two degenerate spin S=1/2 doublets of opposite chirality. Due to lack of inversion symmetry in the molecule these two states are coupled by an external electric field, even when spin-orbit interaction is absent. The spin-electric coupling can be viewed as originating from a modified exchange constant δJ induced by the electric field. We find that the calculated transition rate between the chiral states yields an effective electric dipole moment d=3.38×10−33Cm≈e10−4a, where a is the Cu separation. For external electric fields ε≈108 V/m this value corresponds to a Rabi time τ≈1 ns and to a δJ of the order of a few μeV.
@article{arxiv.1008.1139,
title = {First-principle studies of spin-electric coupling in a $\{Cu_3\}$ single molecular magnet},
author = {M. Fhokrul Islam and Javier F. Nossa and Carlo M. Canali and Mark Pederson},
journal= {arXiv preprint arXiv:1008.1139},
year = {2010}
}